Musical instrument pushbutton key operated switch with adjustable plunger key cap

ABSTRACT

The embodiment of the invention disclosed herein is directed to a keyboard construction and electrical connection between a keyboard and its associated tone generators which electronically produce musical sounds. Each of the keys of the keyboard has associated therewith a switch structure which has a selfadjusting stem and stem cap which initially extends a distance greater than is ordinarily required during operation. When the keyboard is initially assembled, the first actuation of the key on the keyboard will depress the actuating stem and cause the stem cap associated therewith to ratchet to a final position where it will always remain. Each of the switches on the keyboard is wired into a matrix which forms part of an encoder logic circuit located at the keyboard. A second similarly constructed decoder logic circuit is associated with the tone generators located within the cabinet of the musical instrument. Time-frame encoding exists between the two logic circuits so that the logic circuit within the organ cabinet knows exactly when one of the keys on the keyboard is depressed to thereby enable the associated tone generator. Only a few wires are needed to interconnect the two logic circuits.

[ June 28, 1974 MUSICAL INSTRUMENT PUSHBUTTON KEY OPERATED SWITCH WITHADJUSTABLE PLUNGER KEY CAP Filed:

Inventors: Richard G. Kallage, .llr., Evanston;

Robert C. Madland, Mount Prospect, both of 111.

Assignee: Illinois Tool Works l1nc., Chicago,

Jan. 2, 1973 Appl. No.: 320.632

US. Cl. 200/159 R, 29/453, 197/102,

ZOO/61.62, 200/172 A Int. Cl. lH0lh 3/12, B4lj 5/16 Field of Search...200/1 R, 86.5, 170 R, 172 R,

200/172 A, 159 R, 159 A, 61.62, 61.81, 61.79, 61.89; 197/98, 102, 103,107;

References Cited UNITED STATES PATENTS Bernin. 340/365 L PrimaryExaminerlames R. Scott Attorney, Agent, or Firm-Ols0n, Trexler, Wolters,Bushnell & Fosse, Ltd.

[57] ABSTRACT The embodiment of the invention disclosed herein isdirected to a keyboard construction and electrical connection between akeyboard and its associated tone generators which electronically producemusical sounds. Each of the keys of the keyboard has associatedtherewith a switch structure which has a selfadjusting stem and stem capwhich initially extends a distance greater than is ordinarily requiredduring operation. When the keyboard is initially assembled, the firstactuation of the key on the keyboard will depress the actuating stem andcause the stem cap associated therewith to ratchet to a final positionwhere it will always remain. Each of the switches on the keyboard iswired into a matrix which forms part of an encoder logic circuit locatedat the keyboard. A second similarly constructed decoder logic circuit isassociated with the tone generators located within the cabinet of themusical instrument. Time-frame encoding exists between the two logiccircuits so that the logic circuit within the organ cabinet knowsexactly when one of the keys on the keyboard is depressed to therebyenable the associated tone generator. Only a few wires are needed tointerconnect the two logic circuits.

1 Claim, 14 Drawing 1F igures Pmmmmze new 3821529 SHEEI 2 OF S MUSICALINSTRUMENT PUSHBUTTON KEY OPERATED SWITCH WITH ADJUSTABLE PLUNGER KEYCAP I BACKGROUND OF Tl-lE INVENTION This invention relates generally toa keyboard construction and electrical interconnection for key actuatedmechanisms and electrical responsive circuits, and more particularly toa keyboard construction and electrical interconnection for electrical.musical instruments such as electronic organs, and the like. While theillustrated embodiment is directed to a keyboard construction forelectronic organs it will be understood that the broad aspectsof theinvention as disclosed and claimed herein can be used in other fieldswithout departing from the general concepts of this invention.

In the manufacture of keyboard instruments such as electronic organs, itis customary to interconnect a substantialnumber of wires betweensub-assemblies such as keyboard switching mechanisms and a plurality oftone generator oscillators located within the cabinet proper of theelectronic organ. This interconnection requires manual connecting, suchas by soldering or the like, of a plurality of wires, one wire betweeneach key and its associated circuit and tone generator. The customarykeyboard switching device of prior art organs is a bus bar typeconnection with a switch contact formed on the key and engaging thebus-bar when the key is depressed during playing. This causes anelectronic signal to be delivered to the appropriate gate circuit toenable the tone generator. Because of the minimum space within thekeyboard support structure, the

tone generator and audio amplifier circuits are housed in the large rearportion of the cabinet which also houses such things as loudspeakers,foot pedal volume controls and the like. The interconnection of aplurality of key switches and a plurality oftone generators is a timeconsuming and expensive proposition, and even with experienced andskilled workmen doing the connecting operations there are sometimesinadvertent misconnections and bad solder joints which cause troublewith the finished product. For example, in a twomanual electronic organhaving foot pedals, there may be as manyas sixty-one keys for eachmanual position thus having a total of one hundred twenty-two (122) keysto be interconnected with one hundred twentytwo (122) different soundsproduced by tone generators. The 122 wires providing thisinterconnection form a relatively large harness or, sub-assembly whichis mounted in the electronic organ cabinet with the terminating ends ofeach wire being fixed in position by soldering or the like. This type ofinterconnection greatly increases the cost of electronic organs becauseof the high cost of labor.

Another consideration when manufacturing keyboards for electronic organsis that adjustment of the bottom position of the key with respectto itsactuating switch is necessary for each of the keys of the keyboard. Thisadjustment takes as long as two minutes in some instances and in a twomanual organ having sixtyone (61) keys per manual, the adjustment timeis in the order of about four hours. This alsosubstantially increasesthe cost of electronic organs of the prior art.

SUMMARY OF THE lNVENTlON Accordingly, it is an object of this inventionto provide a new and improved keyboard structure which substantiallyeliminates the need for manual adjustment of each key.

Another object of this invention is to provide a new and improvedcircuit arrangement whereby the interconnection between a plurality ofkeys on a keyboard and a plurality of tone generators is accomplishedwith a minimum number of interconnecting wires.

A more specific object of this invention is to provide a new andimproved electronic musical instrument which has a keyboard constructionand electrical interconnection which is efficient and reliable inoperation and simple and inexpensive to manufacture.

Briefly, the present invention relates to a switch and a switchingsystem which has particular adaptation for electronic musicalinstruments such as organs and pianos. There are two physicallyspaced-apart logic circuits which rapidly scan a matrix switchingarrangement associated with each of the keys on either a one or a twomanual keyboard. The interconnection between the spaced-apart logiccircuits is accomplished with as few as three wires, one for the clockgenerator signals, one for the output control signal in a giventime-frame, and one wire for the interconnection of power between theelectronic circuits. There is therefore no need for interconnection ofeach switch of the keyboard with its corresponding tone generator asthis is now accomplished by proper timing of the encoder and decoderlogic circuits.

The matrix arrangement disclosed herein has capabilities of 128 matrixpoints and is therefore well suited for use in a two manual keyboardarrangement having 122 keys. The clock pulse generator will produce aseries of clock pulses, the first one of which is termed a mark pulseand each pulse thereafter representing a given time-frame position. Thetwo spaced-apart logic circuits are therefore operated in unison withone clock pulse generator so that each time-frame position at thespaced-apart logic circuit represents whether or not its associated keyat the keyboard is depressed. lf a key is depressed, a pulse isgenerated into that time-frame and transmitted along a single wire tothe second computer in the electronic organ cabinet. This secondcomputer then energizes a tone generator circuit associated with thatparticular time-frame to produce the audio signal desired. The markpulse which initiates each cycle of operation can be generated from areset signal which may be located in a different place within thetime-frame than all of the. other pulses so that at the completion of acount of 128 pulses the restart or mark pulse will reset all of thelogic circuits to an initial condition regardless of their state.

The other aspects of this invention is the incorporation of a mechanicalswitch structure which allows automatic adjustment of the switch withrespect to the associated key, this automatic adjustment taking placeupon the first manual actuation of the key. The particular switchdisclosed herein is of the solid state type having a magnetic toroidalcore structure through which passes two or more wires. One of the wiresis a drive wire and another wire a sense wire so that signal couplingbetween the drive and the sense wire occurs only when the saturatedstate of the toroidal magnetic core is removed. The magnetic state ofthe toroidal magnetic core changes when the switch stem is actuated. Aunique stem and ratchet arrangement is provided for each switch so thatwhen the key of the keyboard is depressed to a bottom or end of travelposition it will drive the stem cap along its ratchet to an end positionwhere it will at all times remain on the stem and move therewith. Thistherefore, eliminates the need for manual adjustment and substantiallyreduces the time to set ments or components.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view ofan electronic organ incorporating the new and improved keyboard switchand electronic circuitry of this invention;

FIG. 2 is a diagrammatic representation of a solid state switchingdevice used in the keyboards of FIG. 1;

FIG. 3 is an operative position of the solid state switch shown in FIG.2;

FIG. 4 is a fragmentary top view of one of the keyboards shown in FIG. 1illustrating the position of the solid state switches utilized herein;

FIG. 5 illustrates a switch structure utilizing a selfadjusting cap inaccordance with one aspect of the present invention;

FIG. 6 is an enlarged fragmentary view showing the initial position ofthe self-adjusting cap on the switch of FIG. 5;

FIG. 7 illustrates the final bottomed position of the self-adjusting capof FIG. 6 after an initial actuation;

FIG. 8 illustrates the relative position of the switches with respect totheir keys prior to self-adjustment;

FIG. 9 illustrates depression of a key and adjustment of the stem cap ofthe associated switch;

FIG. 10 is a block diagram illustrating the basic components of thespaced-apart logic circuits for control between the keys of the keyboardand their associated tone generators;

FIG. 11 illustrates a time sequence of pulses to show the operation of atime-frame encoding system;

FIGS. 12a and 12b illustrate the detailed logic circuits in accordancewith this invention; and

FIG. 13 is an alternate form of a switch constructed in accordance withthis invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Now referring to thedrawings, FIG. 1 illustrates an electronic musical instrument 10 whereina novel switching structure and arrangement is utilized in accordancewith the principles of this invention. The electronic musical instrument10 is here shown as a two-manual organ which comprises a cabinet 12having a keyboard portion 14 and a speaker portion 16 arranged in awell-known configuration. A speaker 17 is positioned at the front of thespeaker portion 16 and is operatively connected to an amplifier and tonegenerator circuit arrangement generally shown by reference numeral 18.The tone generator and amplifier may be any one of a plurality ofwell-known types used to produce melodic tones in response to manualmanipulation of the keys located at the keyboard portion 14.

The keyboard portion 14 has first and second keyboards 20 and 22 shownfor the two-manual organ. However, it will be understood that a singlekeyboard can be incorporated when the invention is used in a singlekeyboard electronic organ or piano, or the like. The keyboard 20 has aplurality of natural keys 23 and a plurality of sharp keys 24 arrangedin the usual piano keyboard configuration. Similarly, the keyboard 22has a plurality of natural keys 26 and a plurality of sharp keys 27 alsoarranged in the piano keyboard configuration. This general configurationis illustrated in FIG. 4 which shows a fragmentary portion of thekeyboard 20.

In the usual manner, prior art electronic musical instruments required awire connection between each of the keys of the keyboard and itsassociated tone generator or tone generator gate circuit. This makes itnecessary to use a relatively large complicated wire harness for theirinterconnection.

In accordance with the present invention, a solid state mechanism 28 isassociated with each of the keys and connected in a matrix circuit ofthe XY" array configuration which forms part of an encoder logic circuit30. Spaced from the keyboard is a decoder logic circuit 31 which isoperatively coupled to the amplifier and tone generator circuit 18. Whenone of the keys on either of the manual keyboards is depressed, aparticular cross over juncture of the X-Y array causes an output signalto be developed from an associated solid state switch 28 and deliveredover a line 32 to the decoder 31. This output signal corresponds to atimeframe encoding arrangement which will energize an associated one ofa plurality of tone generators so that a sound can be electronicallyproduced in response to actuation of a particular one of the keys on thekeyboards. This output pulse travels over the single wire 32 andidentifies any one of the plurality of keys on either of the keyboards.To maintain synchronization of the encoder 30 and the decoder 31, aclock pulse is delivered to both simultaneously over a line 33, and theclock generator can be located at either location. Because of spacelimitation, it may be desirable to place the clock generator at thedecoder 31. Power is delivered to the encoder and decoder over a line34. Therefore, instead of having the usual one hundred twentytwo I22)cables connected between the keyboards 20 and 22 and the tone generatorcircuits 18, only three wires are now needed to operate the electronicmusical instruments.

While most any type of switching mechanisms can be used in accordancewith the principles of this invention, the preferred switching device isa solid state switch as illustrated in FIGS. 2 and 3. The basic conceptsof this switch are shown in US. Pat. No. 3,638,221. The operationaltheory of the solid state switch incorporated in the keyboards disclosedherein utilizes a U-shaped magnetic support member 36 having a pair ofspaced-apart legs 37 and 38. Mounted to the lower ends of the legs 37and 38 are a pair of magnets 39 and 40, respectively, which arediametrically opposed and on opposite sides of a magnetic toroidal core41. Passing through the magnetic toroidal core 41 A are in a pair ofconductive wires 42 and 43, one of which is a drive line wire and theother of which is a sense line wire. When the magnets 39 and 40 arepositioned as shown in FIG. 2, the magnetic toroidal core 41 is in amagnetically saturated condition. Therefore,

pulse signal information which is delivered along the drive line 42 willnot be transformer coupled to the sense line 43 as a result of themagnetically saturated condition of the core. However, when the U-shapedmagnetic support member 36 is depressed as shown in FIG. 3, thisdisplaces the magnets 39 and 48 to unstaturate the magneticcore andallow pulse signal information to be transformer coupled from the drivewire 42 to the sense wire 43.

Each of the U-shaped magnetic support members 36 has extending therefroma switch stem 46 which is engaged with the key stick of its associatedkey of the keyboard to be depressed when the key is actuated. Theparticular physical configuration of switches can vary without departingfrom the scope of this invention, and one form may be that as shown in FIG. 4. Here a plurality of switches 28 are aligned in a row immediatelybeneath the natural keys 23 while a second plurality of switches 28 isaligned in a row beneath the sharp keys 24. While the switches are hereshown as being immediately beneath the keys, these switches can beplaced behind the key sticks and actuated by the key stick or by anactuating extension lever extending therefrom as shown in FIG. 13. Thearrangement of the switches 28 and their associated toroidal cores 41may be similar to that as set forth in a Bernin application Ser. No.259,209, filed June 2, 1972, and assigned to the same assignee.

Referring now to FIG. 5 the details of construction of one of theswitches 28 is shown having certain features which will allow forautomatic adjustment of the length of the switch stem. Here a switchbody 47 is inserted through a support plate 48 and firmly held inposition by spaced-apart flange members 490 and 49b. Formed along theswitch stem 46 is gripping means 50 preferably being closely spacedteeth-like members as best shown in FIGS. 6 and 7. However, it will beunderstood that the gripping means 50 can take other forms to achievethe same function. A stem cap 51 is positioned over the stem andarranged to engage the gripping means at the end most position along thestem so its initial length is longer than need be. When the switch ismounted in position under its associated key and actuated by depressingthe key, the stem and stem cap will travel downwardly until the switchactuating mechanism within the switch body 47 bottoms. Once thisbottoming action occurs further travel of the associated key will causethe stem cap 51 to automatically ratchet or move along the grippingmeans 50 to its final position as shown in FIG. 7. Thereafter when thekey is actuated'the switch will travel to its bottom position withoutresistance and without causing overtravel of the switch mechanism whichwould otherwise tend to increase switch wear.

To better understand the automatic adjustment feature of the switch stemand stem cap in connection with its associated key on a piano typekeyboard reference is now made to FIGS. 8 and 9. Here a plurality of keysticks 54 are associated with each of the keys 23 and 24. Positionedbeneath the row of key sticks 54 is the support plate 48 upon which ismounted a plurality of switches 28. The key sticks are pivotally securedto means, not shown, at a pivot point 56 in a well known manner so thatdepression of the end of the key, as shown in FIG. 9, will cause pivotalmovement of the key about the pivot point 56. The actuating mechanismwithin the switch housing will bottom to stop further travel thereofand. the stem cap 51 will be ratcheted or urged along the grippingsurface 58 to a height which corresponds to the bottom position of thekey stick 54. The amount of travel of the stem cap 51 is determined bythe distance between the key stick 54 and an associated stop member 57.When the key is released spring means will pivot the key stick about thepivot point 56 to its upper position and spring means within the switchhousing will raise the stem 46 and stem cap 51. The overall length ofthe stem and stem cap is now permanently fixed for all subsequentactuations of the key and bottoming of the key and key stick will occursimultaneously with bottoming of the switch so that the same actuatingcharacteristic is obtained for each manual manipulation. This then alsoallows uniform keyboard feel to the player of the electronic musicalinstrument. Mounted below the switches 28 may be a printed circuit boardstructure 60 which has mounted thereon the matrix and encoder circuit inaccordance with the principles of this invention.

Referring now to FIG. 10 a general block diagram of the novel circuitarrangement utilized in accordance with this invention is illustrated.Also to be considered at this time is the wayform configuration of FIG.11. Here the logic circuit 30 comprises an encoder 61 having an outputline thereof coupled to a drive circuit 61, which, in turn, is connectedto a matrix network 63. Preferably the matrix of network 63 is of the XYconfiguration having a plurality of cross line junctures which representspecific points to be electrically scanned. The output of the matrix 63is coupled to a multiplex circuit 64 so that a pulse signalcorresponding to an output of one of the junctures of the matrix can bedelivered to a pulse stretcher circuit 66. This output signal is thendelivered over a line 67 to a terminal 68 which connects the output line32 between the two logic circuits 30 and 31. It will be recalled thatthe logic circuit 31 is at a remote location relative to the logiccircuit 30 which is positioned next to the keyboard arrangement. Thematrix 63 and multiplex unit 64 together with the other components ofthe logic circuit 38 may conform substantially to that disclosed inapplication Ser. No. 339,476, filed Mar. 8, 1973, which is acontinuation of application Ser. No. 144,902, filed May 19, 1971, nowabandoned.

In accordance with this invention a memory circuit 69 receives theoutput pulse from the pulse stretcher 66 and provides a feedbackconnection over a line 70 to the multiplexer 64. This feedback forms ahysteresis loop to eliminate extraneous pulse signals from the matrixcircuit.

The encoder 61 is driven by a count register circuit 71 which receivesclock pulses over the synchronizing line 33. The clock generator circuitis located in the logic circuit 31 it being understood that it can alsobe located in the logic circuit 30. A clock pulse generator 72 istherefor coupled to the count register 71 and to the count register 73which forms part of the remote logic circuit 31.

The output of the count register '73 is delivered to one of the inputsof the plurality of AND gates 74 which have the other inputs thereofcoupled to the output line 32 to receive the time-frame coded outputsignal. Therefore as the AND gate 74 is scanned one at a time as aresult of energization by the count register 73 the particular outputpulse associated with a given time-frame will actuate only one of theAND gates 74,

this AND gate being associated with a particular one of the plurality ofkeys at the keyboard. This output signal is then delivered to a decodercircuit 76 which is driven in time sequence with the encoder 61 so thata particular one of the plurality of flip-flop circuits 77 is energized.This will set one of the inputs of a plurality of AND gates 78 to allowpassage of an electronically generated tone from a particular one of aplurality of tone generators 79. This tone generator signal is thendelivered to an audio-amplifier circuit 80 which, in turn, isoperatively connected to the speaker 17 for energizing the same.

P10. 11 illustrates the spacing between clock pulses 81 which controlsoperation of the count registers 71 and 73. The output of the pulsestretcher as shown by the wayform 82, and the scanned pulse as shown bythe wayform 83. The output pulse corresponding to the actuation of aswitch is shown at 84 while the output pulses which do not appear areshown in phantom lines at 86. A marked pulse 87 illustrates thebeginning of a given cycle. 1

Referring now to FIGS. 12A and 12B a detailed block diagram of the logiccircuit 31 utilized at the keyboard is illustrated; Here it can be seenthat the matrix 63 comprises a plurality of X lines coupled to a pair ofXline scan decoders 90 and 91 which comprise part of the decoder circuit61. Coupled to the X line scan decoders 90 and 91 are NAND gates 92 and93 respectively to synchronize actuation of each of the outputlinesthereof in a sequential manner. The input signal from the clock 72 isdelivered to an input tenninal 94 which may pass through a pair ofseries connected inverter amplifier circuits which has the output of oneof them coupled first to a NAND gate 98 and then to an input of thefirst flip-flop circuit 99. The flipflop circuits illustrated herein areof the 1K type, it being understood that other flip-flops ofthe toggleconfiguration can be used.

The output of flip-flop circuit 99 is coupled to a second flip-flopcircuit 100 which, in turn, is coupled to a flip-flop circuit 101. Theflip-flop circuit 101 is connected to a flip-flop 102 and to a pair oflines 103 and 104 which are inputs to the X scan decoders 90 and 91. Theoutput of flip-flop circuit 100 is also connected to a pair of inputlines 106 and 107 which are also inputs to the Xscan decoders. Theoutput circuit of flip-flop circuit 102 is coupled to the input of aflip-flop circuit 108 and to a pair of lines 109 and 110 coupled to theinput of the X scan decoders 90 and 91, respectively. This then willprovide logical sequencing of the X lines of the matrix one at a timefrom, for example, the first line on the left to the last line on theright, or in the other direction if desired. To scan the Y lines of thematrix 63 the output of the flip-flop circuit 108 is delivered to stillanother flip-flp circuit 111 which, in turn, is coupled to a flip-flopcircuit 112 and to a pair of NOR gates 113 and 114 over a line 116. Theoutput of flip-flop circuit 112 is also connected to a flip-flop circuit117 and to one of the inputs of the NOR gate 113 and to a NOR gate 118.A fourth NOR gate 119 has one input thereof coupled to the low stateoutput of flip-flops circuit 113 and the other input thereof coupled tothe low state output flip-flop circuit 111. When flip-flop circuit 117is energized it completes the sequence of one cycle to produce a markpulse output through a pair of series coupled inverter circuits 120 and121.

To control sequential energization of the Y lines of the matrix aplurality of AND gates designated as a group by reference numeral areintercoupled with NOR gates 113, 114, 118, and 119 so that the eight Ylines are energized one at a time while 16 lines are scanned during eachenergization of a Y" line. In other words, a Y" line is set to a highstate or energized while all of the 16 X lines are scanned. Thisoperation repeats until all of the Y lines are scanned and then thefirst Y" line is again scanned to restart the cycle. This restarting ofthe scanning of the Y lines will produce the mark pulse, as shown at 87in FIG. 11, necessary for each cycle of operation. The plurality of ANDgates 125 and the NOR gates connected thereto form a part of themultiplex circuit 64 together with a pair of amplifier integratedcircuit units 127 and 128 of FIG. .128. The signal produced as a resultof depressing one of the keys which has its associated switch at thejuncture of the X-Y lines will be amplified through these amplifiers anddelivered to a summer and buffer amplifier circuit 129. The output ofthe buffer amplifier 129 is delivered to a NOR gate 130 which forms athreshold detector so that only pulse signals of a predeterminedamplitude will be delivered to the pulse strecher 70.

The pulse stretcher 70 is formed by a pair of crosscoupled NAND logiccircuits 131 and 132 to produce the output pulse to be delivered to theterminal 68 through an inverter circuit 133. The serial memory circuit69 is coupled back to the amplifier circuits 127 and 128 over the line70 through an inverter circuit 134 so that a cancellation signal can beapplied to a cancel line 136 associated with the matrix. This cancelline eliminates the possibility of extraneous transformer coupling ofsignals from the drive line to unselected sense lines.

A modification of the switching arrangement in accordance with thisinvention is illustrated in FIGS. 13. Here an alternate embodiment ofthe automatic adjustment of the actuating plunger or lever isincorporated in a switch designated generally by reference numeral 150.The switch includes a switch body 151 connected to aprinted circuitboard 52 by having the drive lines 153 and sense lines 154 connected tothe printed circuit board by soldering of the end terminals insertedtherethrough. The X-Y array of the matrix may be formed on the back ofthe printed circuit board.

An arcuately shaped gripping member 156 is formed along a lever 157 sothat a tooth portion 158 of a magnet carrier 159 can move relativethereto when the magnet carrier reaches its stop position. To achievethis a pair of diametrically opposed stop members 160 and 161 areprovided so that the switch can be inserted in either orientation. Astop portion 162 is positioned below the switch so that when the keystick 54 is raised, by depressing its associated key cap, it will raisethe lever 157 to pivot the magnet carrier 159 downwardly until itengages the stop 162. Once the stop member 160 engages the stop 162further travel of the key stick 54 will cause a ratcheting actionbetween the gripping portion 156 and the teeth 158. This will cause therelative angular position between the lever 157 and the magnet carrier159 to change so that when the key is bottomed by a full depressingaction so also is the switch actuating mechanism engaged with its stop.

While several specific embodiments of the invention have beenillustrated herein it will be understood that variations andmodifications may be effected without departing from the spirit andscope of the novel concepts disclosed and claimed herein.

The invention is claimed as follows:

1. A keyboard construction for electronic organs comprising a manuallyoperated key operatable about a pivot point to move from a firstorientation to a sec ond orientation upon actuation of said key, a stopmeans for stopping said key at said second orientation, an electricswitch associated with said key having a depressable actuating plungerextending toward said key,

a key cap on said plunger, said cap and said plunger having grippingmeans formed thereon which are con structed so as to allow said cap tobe forced on said cap from an initial position, at which said plungerextends into said cap by a minimum amount when said key is at its firstorientation, to a final position, at which said plunger extends intosaid cap by an additional amount corresponding to the actuation of saidkey to said second orientation so that said cap and said plungerthereafter retain their relative positions upon release of said key tosaid first orientation.

1. A keyboard construction for electronic organs comprising a manuallyoperated key operatable about a pivot point to move from a firstorientation to a second orientation upon actuation of said key, a stopmeans for stopping said key at said second orientation, an electricswitch associated with said key having a depressable actuating plungerextending toward said key, a key cap on said plunger, said cap and saidplunger having gripping means formed thereon which are constructed so asto allow said cap to be forced on said cap from an initial position, atwhich said plunger extends into said cap by a minimum amount when saidkey is at its first orientation, to a final position, at which saidplunger extends into said cap by an additional amount corresponding tothe actuation of said key to said second orientation so that said capand said plunger thereafter retain their relative positions upon releaseof said key to said first orientation.